In medical therapy using therapeutic substances which are administered to a body, aimed at a particular local target such as an organ or a lesion in an organ, it is of substantial interest to know how the administered substance is accumulating in the body, and especially if the therapeutic substance is accumulated in the intended target region. The latter may be a lesion in an organ, such as a tumor, or a certain functional structure in an organ.
The former is inherently clear for the administration of a therapeutic substance which comprises a radionuclide intended for the treatment of a lesion in an organ, in particular of a tumor. In this case, it is of particular interest to be able to control or monitor where the radionuclide accumulates in the body, because it is intended to radiate only the target area and to minimize the exposure and thus the damage to all other regions of the body. Another case pertains to the administration of a chemical substance, such as in chemotherapy, which is not radioactive per se, but wherein its molecules are labelled with an additional radionuclide which serves the purpose of enabling the monitoring of the distribution of the therapeutic substance in the body by monitoring the emitted radiation from an outside of the body.
Various techniques have been proposed to determine localized concentrations of radioactive substances administered to a body, which often rely on a combination of two different imaging techniques. Examples are combinations of SPECT with CT and PET with CT, which both allow for quantitative measurements of radiation, however both only post-therapeutical and not during therapy.
U.S. Pat. No. 5,844,241 A proposes a combination of planar imaging and computer tomography (CT) data for dosimetry purposes in radio immune therapy. U.S. Pat. No. 7,291,841 describes a wearable detector array for SPECT, PET, and Compton scatter imaging in nuclear medicine. In “Toward Simultaneous Real-Time Fluoroscopic and Nuclear Imaging in the Intervention Room” by C. Beijst et al., Radiology, p. 142749, June 2015, a fusion of fluoroscopy and nuclear imaging is described.
The known techniques leave room for improvement in that they typically either do not allow measurement during therapy, lack near-real-time-characteristics, and/or have to compromise between spatial resolution and the ability for delivering the required information in near real time. Generally, there is also room for improvement with respect to the delivered spatial resolution and achievable precision of the delivered data.
In view of the above and for other reasons, there is a need for the present invention.